Method of treating sugar



Patented Apr. 12, 1927.

UNITED STATES PATENT OFFICE.

HENRY C. WELLE, OIEiCROCKETT, CALIFORNIA.

METHOD OF TREATING SUGAR.

No Drawing.

This invention relates to the treatment of sugars and particularly to the treatment of soft sugars (commonly known as yellow or brown sugars) such as are produced by sugar refiners to be used for direct consumption, for baking and for cooking.

The process of making soft sugars at the present time varies considerably in different refineries, but the practice which has heretofore been used may in general be stated to be somewhat as follows:

For a base, impure sugar liquors or syrups such as syrups from granulated sugars, or raw aflination or wash syrup or the regular granulated sugar liquors from the char filters may be used. These bases are generally selected so as to have a purity between and 88, the exact purity depending on the type of material used and the type of sugar produced. This product is generally, but not always, given a special char filtration, the extent of this depending on. the base selected, the color desired in the product produced, and other considerations. For example, if a syrup from granulated sugar is used as a base it will need relatively little or even no char filtration, as the liquor from which it was originally produced has already a had considerable char filtration. On the other hand, where such dark material as affination syrup is used it will require considerable char filtration in order to produce the required color.

After char filtration the material is sent to the pan floor to be boiled in the vacuum pans. Here the material may be boiled direct or may be boiled with syrups returned from previous strikes, depending on the color of su ar' that is desired.

After boi ing, the massecuite is spun out in such a wa that a small amount of syrup is left adhering to the sugar so as to give it the desired color and flavor. The sugar is then generally given a certain amount of aeration and packed for shipment.

It will be understood that there are a great many modifications of the above practice used by different refiners, but the above outline will approximately cover most of the methods heretofore in use.

In producing these soft sugars it is desired that they have a bright, clear, yellowgolden color that will not change on storage. However, in practice, it is found that the sugars produced by the above practice often have a dull, dirty appearance, the extent of mon phosphate salts,"

Application filed October 1, 1923. Serial No. 665,949.

this varying considerably. Even if originally produced with a fair color, it frequently happens that a dark dirty color is gradually developed on storage. It is the principal object of the present invention to so produce a soft sugar as to insure that it will acquire and maintain a desirable color.

Investigation has indicated. that this difficulty with the color is due to the presence of iron compounds, probably iron polyphenols. These compounds are probably formed in the various operations in the refinery,

through some-of them may be present in the original rawsugars. As these iron polyphenols are very dark in color, a small quantity of them will greatly modify the appearance of the sugar. ,It is believed that the ferric forms are much darker than the ferrous forms, therefore the development of this dark color on standing is believed to be due to oxidation.

It has been found that by the use of solutions containing phosphate ions (that is, PO anions) this dark coloring matter can be broken up. This is done by the application of solutions of phosphoric acid or phosphate salts, the iron polyphenols being decomposed with the precipitation of iron phosphate and the liberation of free polyphenols. lVhile these free polyphenols possess a certain amount of color, it is not.objectionable-in fact is probably a desirable coloring matter to have in the sugar. The iron phosphate is light in color and so'produces no harmful effect on the color of the sugar;

In practice the phosphoric acid or phosphate salts may be applied inseve'ral different ways. It is found that the most satisfactory point in the process at which to apply the prosphoric oxide salts to the sugar is in the centrifugals after the bulk of the adhering syrup has been spun off, or to the sugar after it has left the centrifugals.-

The actual application of phosphoric acid or phosphoric acid salts may be carried on as follows: A solution is made up containing twenty per cent phosphoric acid, (H POQ or its P 0 equivalent in acid calcium phos phate, acid sodium phosphate or other comto use them in the acid form). This is added to the sugar centrifugal just before or just (it being preferable as it is being emptied, in such quantities as will give about 0.1 per cent of H 1 0 on the weight of sugar in thecentrifugal. If the material is added with a cup, it isthrown into the basket of the centrifugal just before the brake is applied. This results in a slight washing of a small portion of the sugar, but in being plowed out and passing through the sugar scrolls the material is thoroughly mixed so that there is no evidence of washing of thesugar, and the entire mass-of sugar becomes treated with the phosphoric acid. If the material isapplied with a spray, it is preferable to apply it While the sugar is bein plowed out or in the scroll beneath the centntugals.

As an example, when forty inch centrifugals holding 400 pounds of sugar are used, two pounds (for approximate work one quartjtis used) of the pre ared solution are thrown on the sugar just efore the brake is 'applied to the centrifugal. If the centrifugal holds only 350 pounds of sugar (as is the case with some grades) a smaller quantity of solution may be used, or the solution may be made more diluteabout 17.5 percent. It

. will be found that the added water in the sugar does no harm for ordinary grades of sugar. After dropping out of the centrifugal the sugar is passed through scrolls that mix it thoroughly and then through an aerating device such as is commonly used for handling soft sugars.

When the phosphoric acid is added it is found that there is a liberation of acetic and other volatile acids, due to the presence of their salts in the sugar. oughly aerated while warm these acids are practically all volatilized and the sugar becomes as alkaline or even more alkaline than before treatment. If not aerated there will be an acidity to the sugar that can be readily detected by tests, though the odor of volatile acids may not be very evident when the sugar is cold. I therefore prefer to give the sugar as thorough an aeration as possible.

l vhile it is stated that 0.1 per cent of phosphoric acid (H PO on the weight of the sugar should be applied, this is only an ap- If the sugar is thor-.

proximate figure and the desired quantity may vary greatly with the circumstances. It is found that it straight phosphoricacid is used, a smaller quantity will sufiice than if phosphoric acid salts are used, and also with light colored sugars a smaller quantity of material may be used than with dark colored sugars. In some cases, with light colored sugars and where a solution of straightphosphoric acid is used, as little as .02 per cent to .03 per cent lT-LPO. on the weight of sugar will sufice, and in other cases with dark colored sugars, it. may be necessary to add 0.2 per cent H P 4 or its equivalent in phosphoric acid salts.

While phosphoric acid alone ,is somewhat more effective then the acid salts, the latter have the advantages that they are somewhat easier to handle and the generation of volatile acids is somewhat less.

Having thus described my invention, what I claim and desire to secure by Letters Patent is:

1.' The process of adding small quantities of a solution containing phosphate ions to soft sugar not in solution, and thoroughly mixing the sugar with the solution to obtain a uniform mixture.

2. The process of adding small quantities of a solution containing phosphate ions to soft sugar, thoroughly mixing the sugar and aerating same suficiently to remove the volatile, acid developed. I

3. The process of refining sugar which consists in addin small quantities of a solution containing p osphate ions to soft sugar after the surplus syrup has been removed, and thoroughly mixing the sugar and phosphate solution. a

4. The process of adding small quantities of a solution containing phosphate ions to soft sugar, after the surplus syrup has been spun off by centrifuging, and thoroughly mixing the sugar and the solution. 

